1. Field of the Invention
This invention relates to brakes and, more particularly, to a brake in which tension and emergency braking are initiated at opposite axial ends of the brake.
2. Disclosure of Related Art
A conventional water cooled disc brake includes a stationary housing disposed about a rotating shaft. A plurality of friction plates are coupled to the housing and fixed against rotation relative to the housing, but axially moveable relative to the housing. These friction plates define fluid jackets through which cooling liquids are circulated. Another plurality of friction plates are coupled to the shaft for rotation therewith and are axially movable relative to the shaft. The plates coupled to the shaft are interleaved with the plates coupled to the housing. An emergency or safety brake actuator is disposed at one axial end of the brake and applies a constant force in an axial direction to bring the plates into contact with one another. A tension brake actuator is disposed at the same axial end of the brake and applies a variable force for controlled braking torque.
In some conventional brakes, the tension brake actuator applies a force in the opposite axial direction relative to the emergency brake actuator and controlled braking is accomplished by the combination of forces from the two actuators. In these brakes, however, the amount of tension braking force that can be applied and the ability to control the tension braking force are limited because of the need to offset the force of the emergency brake actuator. Commonly assigned U.S. Pat. No. 6,029,782 discloses an improved brake in which an additional actuator is employed to counter the force applied by the emergency brake actuator. In this manner, tension braking is made responsive solely to the tension brake actuator. Although the brake in U.S. Pat. No. 6,029,782 represents an improvement relative to previous brake designs, the improved brake suffers from packaging limitations and renders maintenance of the brake actuators and other brake components relatively difficult. Further, the brake design cannot be readily applied to modify existing brakes having only a tension brake actuator. Rather, substantial modifications to the brake are required.
The inventors herein have recognized a need for a brake that will minimize and/or eliminate one or more of the above-identified deficiencies.